Forage production and persistence characteristics of grazed native warm-season grass mixtures with or without nitrogen fertilizer

Abstract

Background: Native warm-season grass (NWSG) mixtures may provide a low-nitrogen (N)-input summer perennial forage option to extensively managed forage–livestock systems. Methods: Mixed pastures of big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium scoparium Michx.), and indiangrass (Sorghastrum nutans L.) fertilized with 0 or 67 kg N ha−1 were continuously stocked with beef heifers and cows. Forage mass, nutritive value, and canopy heights were determined every 2 weeks during the grazing season. Stand persistence measures included the canopy cover and leaf area index (LAI) and plant crown density at spring emergence following 3 years of grazing management. Results: Forage mass, canopy height, and stocking densities were greater for N-fertilized NWSG than unfertilized NWSG for the first 30 days of the growing season across the 3-year study. Forage NWSG fertilized with N had a greater decrease in LAI during the growing season (51% decrease) than unfertilized NWSG. Spring NWSG plant density estimates following 3 years of grazing did not differ across N management strategies. Conclusions: Forage NWSG mixtures supported superior forage attributes and greater stocking densities early in the grazing season under low-level N than zero-N-input systems and may provide a low-N-input alternative for improved species use in southeastern US forage–livestock systems.